如何阻止这种线程？

Question

I have one thread that has this code

while(!this.isInterrupted()) {
    try {
        socket = server.accept();
    }
    catch(IOException e) {
        continue;
    }
}

When I call interrupt method from somewhere then it will stop executing only if it is checking condition. What if the program is at server.accept() statement? It will not stop till any request comes from any socket. I want that when I call interrupt method this should stop immediately. Is there any solution for this problem.

Answer 1

Override the interrupt() method in your Thread like this:

@Override
public void interrupt() {
    super.interrupt();
    socket.close();
}

When another thread interrupts this thread, the socket will get closed. When the thread is currently inside accept() , accept will exit immediately by throwing a SocketException . Your catch-block will catch that exception ( SocketException is a subclass of IOException ) and the check in the while-statement will be performed, which will then notice that the isInterrupted() flag is set and exit.

In contrary to the currently accepted solution it will exit immediately and not wait for up to 10 seconds to do so.

Answer 2

You could set a timeout on your ServerSocket:

server.setSoTimeout(10000);

When you call the accept method now, it will accept new connections for 10 seconds, after that it throws a SocketTimeoutException. Then you can do your accept again.

Answer 3

Well, you could use the deprecated destroy() method to stop brutally murder the thread, but you really shouldn't do that because you don't know what it is doing at that moment. Chances are the accept-method is currently in the middle of some operation which must not be interrupted without cleanup.

A better solution would be to call server.close() from another thread. In that case the accept will exit by throwing a SocketException .

To allow another thread to do this, you either need to expose a reference to your server-socket somehow, or you need to add a public method to your Thread-class which can be called from another thread and which then calls server.close() . The best obtion depends on how the code around the snippet you posted looks.

Answer 4

You could extend ServerSocket and override the implAccept() method to instead have a timeout and check for the interrupt flag.

Or you could create another thread that monitors the parent thread status and closes the socket when you interrupt it.

public void close()
           throws IOException
Closes this socket. Any thread currently blocked in accept() will throw a SocketException.
If this socket has an associated channel then the channel is closed as well.